Re: [hobbicast] Foundry design help

Kirk Usually, what determines the clearance around the crucible is the room needed to get grasping tools between the crucible and the furnace wall. A number 1

Message 1 of 11
, May 10, 2013

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Kirk
Usually, what determines the clearance around the crucible is the room
needed to get grasping tools between the crucible and the furnace wall.
A number 1 crucible measures 3-4" across the top.
A number of other members and I built what we call a coffee can
furnace. It uses the metal 2 lb coffee cans for a shell. It is about the
right size for a #1 clay graphite crucible which holds about 1 lb of
molten aluminum. I built mine in two parts. I lined the bottom with
refractory for durability. I lined the sides with two layers. The outer
layer is 1" kaowool. I used refractory for the second inner layer for
durability. I lined the upper part with 1 1/2" kaowool which I coated
with two coats ITC100.
I burner I have was a gift. It is a 1/4" Mikey design.

The burner needs to be located so the flame enters the furnace
tangentially. Blasting the burner directly onto the crucible will
destroy the crucible in a short time.

Rupert

On 5/10/2013 5:57 AM, kirkbecnel wrote:
> I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
>
> My question is mainly how large of an area do I need around the crucible?
>
> I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
>
> I am currently building the 3/4" burner in Mike Porter's book.
>
> How much of a gap do I want in between the crucible and the furnace lining?
>
> Thanks

The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.

A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!

Cheers Wonk

--- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@...> wrote:
>
> I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
>
> My question is mainly how large of an area do I need around the crucible?
>
> I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
>
> I am currently building the 3/4" burner in Mike Porter's book.
>
> How much of a gap do I want in between the crucible and the furnace lining?
>
> Thanks
>

kirkbecnel

That is really nice. I don t recall if I have all the pieces for the 1/2 burner or not. I may have gotten them. I was going to build the furnace in the book

Message 3 of 11
, May 10, 2013

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That is really nice. I don't recall if I have all the pieces for the 1/2 burner or not. I may have gotten them. I was going to build the furnace in the book with a propane tank but I did not want to really go that big and I have a small party balloon tank about the size of a freon tank I am employing.

I think I will also put the refractory at the bottom. I don't know if what I have is 2300 or 300 degree, but I know it is up there.

--- In hobbicast@yahoogroups.com, "Wonk" <tiwonk@...> wrote:
>
> Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
>
> <http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
>
> The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
> Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
>
> A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
>
> Cheers Wonk
>
> --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@> wrote:
> >
> > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
> >
> > My question is mainly how large of an area do I need around the crucible?
> >
> > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
> >
> > I am currently building the 3/4" burner in Mike Porter's book.
> >
> > How much of a gap do I want in between the crucible and the furnace lining?
> >
> > Thanks
> >
>

mikey98118

The smallest MIG tip is called .023 because it is meant to run that size wire, but its orifice sizes actually run between .030 and .031 ; this isn t an ideal

Message 4 of 11
, May 11, 2013

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The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.

Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".
Mikey

The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?

Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.

A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!

> I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.

>

> My question is mainly how large of an area do I need around the crucible?

>

> I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.

>

> I am currently building the 3/4" burner in Mike Porter's book.

>

> How much of a gap do I want in between the crucible and the furnace lining?

>

> Thanks

>

[Non-text portions of this message have been removed]

Wonk

I just measured my 3/8 and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and

Message 5 of 11
, May 11, 2013

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I just measured my 3/8" and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and tend to grab while drilling so use a good lube and go slow. I think I used 'tap magic' when I built with drilled mig tips?

Wonk

--- In hobbicast@yahoogroups.com, michael.a.porter@... wrote:
>
> The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.
>
> Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".
> Mikey
>
> ----- Original Message -----
> From: Wonk <tiwonk@...>
> To: hobbicast@yahoogroups.com
> Sent: Sat, 11 May 2013 02:51:27 -0000 (UTC)
> Subject: [hobbicast] Re: Foundry design help
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> Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
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> <http://web.mail.comcast.net/zimbra/h/%3Cspan%20class=" yui-spellcheck?>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc" target=_blank>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
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> The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
>
>
> Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
>
>
>
> A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
>
>
>
> Cheers Wonk
>
>
>
> --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@> wrote:
>
>
> >
>
>
> > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
>
>
> >
>
>
> > My question is mainly how large of an area do I need around the crucible?
>
>
> >
>
>
> > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
>
>
> >
>
>
> > I am currently building the 3/4" burner in Mike Porter's book.
>
>
> >
>
>
> > How much of a gap do I want in between the crucible and the furnace lining?
>
>
> >
>
>
> > Thanks
>
>
> >
>
>
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>
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> [Non-text portions of this message have been removed]
>

Dan Brewer

If you have problems sourcing capillary tubing hypodermic needles for vet care come in all of the sizes you need for small burners. Use a larger mig tip if

Message 6 of 11
, May 11, 2013

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If you have problems sourcing capillary tubing hypodermic needles for vet
care come in all of the sizes you need for small burners. Use a larger mig
tip if you do not have the capability to drill (small drills ) Most of them
will fit . To capture the tubing use silver bearing solder. You can but it
in most welding shops and some ace hardware stores. If using the hard
solder silver/bronze use black flux. If using soft solder silver/tin/zinc
you can use white flux.

> **
>
>
> I just measured my 3/8" and indeed it is .024, guess that was in memory
> since I used cap tube for that build! Mig tips are made of a fairly soft
> copper and tend to grab while drilling so use a good lube and go slow. I
> think I used 'tap magic' when I built with drilled mig tips?
>
> Wonk
>
> _Snip-

[Non-text portions of this message have been removed]

mikey98118

Wonk, Between you and Dan, you have the picture; as Dan pointed out, MIG tips come in various orifice sizes; I list them in a chart of MIG tips found in my

Message 7 of 11
, May 12, 2013

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Wonk,
Between you and Dan, you have the picture; as Dan pointed out, MIG tips come in various orifice sizes; I list them in a chart of MIG tips found in my first book. So, by measuring actual outside diameter of a given cap tube, and choosing the nearest MIG tip orifice to it, then using Gene's "drill gently and use the right lubricant" advice, enlarging an orifice size a few thousandths of an inch, even in soft copper tubing, doesn't have to be challenging.

I would like to add that, of all the burner sizes I've built between 1/4" and 2", 3/8" is the most forgiving size when trying to match up the gas jet orifice with mixing tube diameters.
Mikey

I just measured my 3/8" and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and tend to grab while drilling so use a good lube and go slow. I think I used 'tap magic' when I built with drilled mig tips?

> The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.

>

> Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".

> The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?

>

>

> Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.

>

>

>

> A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!

> > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.

>

>

> >

>

>

> > My question is mainly how large of an area do I need around the crucible?

>

>

> >

>

>

> > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.

>

>

> >

>

>

> > I am currently building the 3/4" burner in Mike Porter's book.

>

>

> >

>

>

> > How much of a gap do I want in between the crucible and the furnace lining?

>

>

> >

>

>

> > Thanks

>

>

> >

>

>

>

>

>

>

>

>

>

>

>

>

> [Non-text portions of this message have been removed]

>

[Non-text portions of this message have been removed]

Bharat

I think you need 6 space both side ways of Pot and 7 in front area at back side it s 10 and for stop heat loss for pot sera wool must be applied in all

Message 8 of 11
, May 12, 2013

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I think you need 6" space both side ways of Pot and 7" in front area at back side it's 10" and for stop heat loss for pot sera wool must be applied in all the wall of furnace another main thing is in side wall of furnce 1.5" pipe must be installed at center level of pot for heat exaust and end of that pipe must be near 1" at chimney. This is best way for melting metal and flame must be 5-6" down than pot for pot safety

> Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
>
> <http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
>
> The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
> Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
>
> A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
>
> Cheers Wonk
>
> --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@...> wrote:
> >
> > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
> >
> > My question is mainly how large of an area do I need around the crucible?
> >
> > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
> >
> > I am currently building the 3/4" burner in Mike Porter's book.
> >
> > How much of a gap do I want in between the crucible and the furnace lining?
> >
> > Thanks
> >
>
>

[Non-text portions of this message have been removed]

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